1. Field of the Invention
The present invention relates to an information processing apparatus, a block detection method, and a program.
2. Description of the Related Art
In recent years, individual identification techniques using biometrics authentication have begun to be introduced. In the individual identification techniques using biometrics authentication (hereinafter referred to as biometrics authentication), biometrics authentication data used for authentication is registered as a template in advance. During the authentication, the previously registered template is collated with biometrics authentication data generated during the authentication.
Normally, in the biometrics authentication, the template used for authentication stores a two-dimensional pattern such as a fingerprint and a vein, and the authentication processing is executed using this two-dimensional image information. In order to improve the accuracy of the authentication processing, Japanese Patent Application Laid-Open No. 2008-269629 suggests a method including the steps of: applying the Hough transformation to the template and the biometrics image generated during the authentication; and authenticating each image to which the Hough transformation has been applied.
By the way, when the authentication processing using the Hough transformation is performed, the number of steps for the authentication processing can be reduced by registering Hough-transformed biometrics images as templates in advance, instead of applying the Hough transformation to the template on each occasion. However, a Hough-transformed image tends to have a larger data capacity than an image in xy-plane to which the Hough transformation has not yet been applied. Accordingly, when a medium with limited capacity such as an IC card stores Hough-transformed images, there is an issue in that the Hough-transformed images are not appropriate in terms of the amount of data. Therefore, it has been desired to develop a method for reducing the amount of data by compressing Hough-transformed images.
In light of the foregoing, it is desirable to provide an information processing apparatus, a block detection method, and a program capable of reducing the amount of data of Hough-transformed images.
According to an embodiment of the present invention, there is provided an information processing apparatus including a Hough transform unit executing Hough transformation on a biometrics image which is image information unique to a living body, and a block detection unit detecting whether a block having a predetermined shape is included in a Hough space image which is a Hough-transformed biometrics image, outputting present position information representing a position at which the block is located in the Hough space image when the block is determined to be included in the Hough space image.
The block may include a plurality of unit blocks, each having a predetermined size, which are connected with a predetermined inclination, and the block detection unit may detect the block by using a plurality of types of blocks in which the unit blocks are connected in different manners and by using a plurality of blocks in which the unit blocks are connected in the same manner but the numbers of unit blocks constituting the blocks are different.
The block detection unit may output the shape of the block, the number of unit blocks constituting the block, and the present position information of the block, which are associated with each other, for each of the blocks included in the Hough space image.
The information processing apparatus may further include a binary conversion unit for converting the Hough space image into binary values based on the number of votes in the Hough space image, and generating the Hough space binary image which is a Hough space image converted into binary values. When the number of votes is equal to or more than a predetermined threshold value, the binary conversion unit may determine that a vote is cast for a corresponding portion, when the number of votes is less than the predetermined threshold value, the binary conversion unit may determine that a vote is not cast for the corresponding portion, and the block detection unit may detect the block on the Hough space binary image.
The block detection unit may detect the plurality of blocks in which the unit blocks are connected in the same manner, in descending order of the number of unit blocks constituting the block.
The block detection unit may change, according to the shape of the block, a position from which detection processing starts as to whether the Hough space image includes the block or not.
According to an embodiment of the present invention, there is provided a block detection method including the steps of executing Hough transformation on a biometrics image which is image information unique to a living body, and detecting whether a block having a predetermined shape is included in a Hough space image which is a Hough-transformed biometrics image, and outputting present position information representing a position at which the block is located in the Hough space image when the block is determined to be included in the Hough space image.
According to an embodiment of the present invention, there is provided a program for causing a computer to achieve a Hough transform function for executing Hough transformation on a biometrics image which is image information unique to a living body, and a block detection function for detecting whether a block having a predetermined shape is included in a Hough space image which is a Hough-transformed biometrics image, and outputting present position information representing a position at which the block is located in the Hough space image when the block is determined to be included in the Hough space image.